24 BULLETIN 11, UNITED STATES NATIONAL MUSEUM. 



This genus includes five species, four of which are now known 

 from the North Pacific. As they are, as a rule, deep-water species, 

 little is known concerning the soft parts. It seems likely that there 

 is a more definite beginning to such a test as that of R. irregularis 

 than has been seen. All the specimens have the appearance of being 

 broken at the lower end. 



RHABDAMMINA ABYSSORUM W. B. Carpenter. 



Rhabdammina abyssorum M. Sars, Forh. Vid. Selsk. Christiania, 1868, p. 248 

 (nomen nudum) — W. B. Carpenter, Ann. Mag. Nat. Hist., ser. 4, vol. 4, 

 1869, p. 288; Proc. Roy. Soc. London, vol. 18, 1869, p. 60.— G. 0. Sars, Forh. 

 Vid. Selsk. Christiania, 1871, pp. 250, 251. — Carpenter, The Microscope, 6th 

 ed., 1881, pp. 562, 563, figs. 321 c, d (in text).— H. B. Brady, Rep. Voy. 

 Challenger, Zoology, vol. 9, 1884, p. 266, pi. 21, figs. 1-13.— De Folin, Le 

 Naturaliste, vol.9, 1887, p. 127, fig. 12a. — A. Agassiz, Bull. Mus. Conip. Zool., 

 vol. 29, 1888, pp. 162, 163, figs. 492, 493 (in text).— Newmayr, Starame Thier- 

 reichs, vol. 1, 1889, p. 173, fig. 17a (in text). — Egger, Abh. kon. bay. Akad. 

 Wiss. Miinchen, vol. 18, 1893, p. 255, pi. 4, fig. 31. — Goes, Kongl. Svensk. 

 Vet. Akad. Handl., vol. 25, no. 9, 1894, p. 19, pi. 4, figs. 67, 68— Schlum- 

 berger, Mem. Soc. Zool. France, vol. 7, 1894, p. 254. — Goes, Bull. Mus. 

 Comp. Zool., vol. 29, 1896, p. 21.— Kimr, Norske Nordhavs-Exp., no. 25, 

 1899, p. 4.— Flint, Rep. U. S. Nat. Mus., 1897 (1899), p. 271, pi. 12, fig. 2.— 

 Rhumbler, Arch. Protistk., vol. 3, 1903, p. 264, fig. 108 (in text). 



Rhabdammina abyssorum, var. robusta Goes, Kongl. Svensk. Vet. Akad. Handl., 

 vol. 19, No. 4, 1882, p. 143, pi. 12, figs. 430, 431. 



Astrorhiza abyssorum Eimer and Fickert, Zeitschr. wiss. Zool., vol. 65, 1899, 

 p. 666. 



Description. — Test free, consisting of a central chamber with 

 three to five radiating arms, usually three, of nearly uniform diameter 

 and usually in the same plane, but occasionally, when there are more 

 than three arms, the extra ones may be in a different plane from 

 the other three, arms tubular, circular in cross section, ends open, 

 forming the apertures of the test, wall of the test composed of very 

 firmly cemented sand grains of variable size, exterior usually rough- 

 ened but the interior smooth, wall fairly thick, cement containing 

 ferruginous material giving the test frequently a reddish brown 

 color, but the color varies from light gray to almost black, according 

 to the materials of which it is composed. 



Diameter, including arms, up to 17 mm. 



Distribution. — The species is well distributed in the North Pacific, 

 occurring in at least fifteen of the Albatross and Nero stations. Of 

 these, one is the station recorded by Goes, D3375, 1,201 fathoms off 

 the west coast of Central America; it was very abundant at D4337, 

 617-680 fathoms off San Diego, California; one station is in Bering 

 Sea, D3501, in 688 fathoms. The other twelve stations were in the 

 region south of Japan in from 71-1,759 fathoms. The species was 

 obtained by the Challenger at station 237, in 1,875 fathoms, east 

 of Japan. 



